In order to remove your funds from a campaign, you need to go into Campaigns -> Click 'Edit' on the campaign you wish to stop -> Change status to 'Stop'
By doing so, the remaining balance will be transferred to your Account Budget, visible on the rightern side when visiting the Dashboard:
Use your account budget in new campaigns
When starting a new campaign, you can use the remaining amount of your account budget simply by changing payment options under the 'Payment' page. Do this by clicking Change ->
Make sure to choose 'Match2One account budget' as your payment option, then hit 'Save'.
Your remaining account budget will now be used to run your new campaign!